JOLIET, Ill. -- A 41-year-old Chicago-area mother and her twin 5-year-old daughters have been found in what authorities are investigating as possible murders and a suicide.

Autopsies are expected Tuesday on the bodies of Celisa Henning and her daughters, Makayla and Addison.

Police wouldn't comment on a cause of death. CBS Chicago reports their bodies were found Monday afternoon in the family's Joliet home by the child's father.

The station reports the deaths are being investigated as an apparent murder-suicide.

Joliet Police Chief Brian Benton said in a statement that the investigation is ongoing and called the deaths a "very tragic incident."

Neighbors say the twins were to start kindergarten this fall at a nearby Catholic school.

The child's grandfather Dennis Henning told the Daily Southtown that his son, who is the girls' father and the woman's husband of 10 years, tried to contact his wife throughout the day but she didn't answer the phone.

He arrived home around 3:30 p.m. and found the bodies, Henning told the paper. All three were found in a bathroom, the paper reports.

"It's a tragedy," Henning told the paper. "I hope and pray to God that he can live through it."

Neighbors told the station they often saw the family outside, the mother gardening and the girls playing with a dog.

"If she did this, I can't imagine the terror in her heart," neighbor Joan Paul told the Daily Southtown. "Those kids were her life. She was an excellent mother."

Neighbor Adele Bryant told CBS Chicago said she just saw the twins a few days ago, when she gave them a gift to celebrate the beginning of kindergarten.

"I happened to come across an art pack of pencils that had strawberries on them," Bryant told the station. "….I wrote them a little note to wish them a happy school year and hopefully they would become great artists."